Pulse-producing snap action switch

ABSTRACT

A snap action switch comprises actuating means operatively connected to a base member and movable from a first position to a second position, a first electrical contact operatively connected with the actuating means and movable therewith from a first to a second position, and a second electrical contact engageable by the first contact at the second position thereof. A resilient member which engages the actuating means carries the first contact with the actuating means until the first and second contacts engage. At this point the resilient member is flexed and released from the actuating means for a period sufficient for a spring to cause the first contact to disengage from the second contact and to snap back to its first position.

United States Patent 2 1 t Robert N. Nannin 3 2,904,661 9 1959 Roeser200/160 [7 1 men or Canoga Park, Cali f. 3,062,071 1 1/1962 Morrow...200/160 X [21] APP] 868,083 3,117,199 1/1964 Millerwise 200/77 [22]Filed Oct. 21, 1969 FOREIGN PATENTS Patented 5, 1971' 962,745 7/1964Great Britain zoo 153.22 [73] Assignee Industrial Electronic HardwareCorp.

New York Primary Examiner-H. 0. Jones Assistant Examiner-Robert A.Vanderhye Attorney-James and Franklin [54] PULSE-PRODUING SNAP ACTIONSWITCH 20 Cl 15 Dr in Fi s.

anus aw g g ABSTRACT: A snap action switch comprises actuating means[52] US. Cl 200/160 operatively connected to a base member and movablefrom a 1 f 13/52 first position to a second position, a first electricalcontact [50] Field of Search 200/160, operatively connected with theactuating means and movable 166 PC; 74/470 therewith from a first to asecond position, and a second electrical contact engageable by the firstcontact at the second [56] References C'ted position thereof. Aresilient member which engages the ac- UNITED STATES PATENTS tuatingmeans carries the first contact with the actuating 2,347,874 1944 ml n200/77 means until the first and second contacts engage. At this point2,215,124 1940 (06k 6! 8| Jim/166 CPC UX the resilient member is flexedand released from the actuating 2,420,913 5/1947 Schellman ZOO/77 meansfor a period sufficient for a spring to cause the first con- 2.722,579 11955 ROhaCS ZOO/150 X tact to disengage from the second contact and tosnap back to 2,748,216 5/1956 Schneider et al. 200/77 i fi t iti n.

PULSE-PRODUCING SNAP ACTION SWITCH This invention relates to electricalswitches, and more specifically to a snap-action switch designed toproduce an electrical signal in the form of a pulse.

Recent developments in the electronics field, particularly in computertechnology, have produced highly advance electrical switches. Theelectrical switching in these devices occurs at seeds in the order ofnanoseconds. Such switching speeds are necessary for the properoperation of the high-speed computers. This fast switching is effectedin electrical circuits without the use of any moving mechanical parts bymeans of such devices as semiconductors arranged in various gatingcircuits. Fast speed switching in electromechanical and mechanicaldevices is considerably slower than in electronic devices.

Despite the slow speed of mechanical switches, there are still a widevariety of applications in which such switches are important. Oneexample is an electric typewriter in which printing is directly relatedto the actuation of an electromechanical switch by manual means, such asthe depression of a typewriter key. As is well known, an electricaltypewriter converts the mechanical displacement of a key into anelectrical pulse signal which is then reconverted into a mechanicalmovement, i.e., printing. It is imperative in this type of device thatthe components which are employed be capable of fast operation.Obviously, the speed at which the complete printing operation occurs islimited by the mechanical movement of the various parts in the system.

Even though some mechanical switches have been developed which arecapable of operating to produce electrical pulses quickly, the qualityof the pulse is often adversely affected by vibrational conditionsduring the operation of the switch. Thus it is not uncommon for switchesof the type now available to produce double pulses or half pulsesbecause of the vibrational shock experienced by the switch during itsoperation. In addition, the presently available high-speed switches areusually quite complex and are expensive to manufacture.

It is the primary object of this invention, therefore, to provide aswitch which quickly and accurately produces an electrical pulse inresponse to a mechanical movement.

It is another object of this invention to provide a switch which isrelatively insensitive to vibrational shock during the operation of theswitch.

It is still another object of this invention to provide a snap actionswitch which when once actuated, quickly and automatically resumes itsinitial operative position so as to be prepared for the next operativecycle.

A further object of this invention is to provide a snap-action switchwhich is adapted to be easily mounted on a printed circuit board.

Broadly the snap-action switch of the invention comprises a base member,actuating means operatively connected to the base member and movable fora first position to a second position, first electrical contact meansoperatively connected in holding engagement with the actuating means andmovable therewith from a first to a second position and secondelectrical contact means engageable by the first electrical contactmeans when the latter is moved to its second position, thereby to closean electrical circuit. Means operatively connected to the actuatingmeans is effective to release the first contact means from holdingengagement with the actuating means when the first and second contactmeans are engaged. At this point, snap means causes the first contactmeans to be snapped out of engagement with the second contact means andrestored to its first position. v

The release of the first contact means from the actuating means and thereturn of the first contact means to its first position occurs at anextremely fact rate promptly after the first and second contacts engage.The actual engagement and disengagement of the first and second contactmeans occurs in a period of approximately 4 milliseconds. Therestoration of the first contact means automatically to its originalposition enables the switch immediately to be in a condition to beactuated again. Thus, the switch is most advantageous for use in adevice such as an electrical typewriter or the like.

As here described the means to release the first contact from theactuating means comprises a resilient member resiliently operativelyconnected between the first contact means and the actuating means. Meansalso operatively connected to the actuating means is effective to flexthe resilient member upon the engagement of the first and second contactmeans thereby to release the resilient member from the actuating means.The release occurs for a period sufficient for the snap means to snapthe first contact means out of engagement with the second contact meansthe back to its first position. in one form of the invention, theresilient member comprises first and second parts and a spring effectiveto urge the parts into engagement with the actuating means. In this formof the invention, means such as an abutment on the actuating means isprovided for separating the spring held parts so that they are releasedfrom the actuating means. The abutment passes through an annulus formedby the parts upon continued advancement of the actuating means andthereby causes the parts to be spread apart and to be temporarilydisengaged from the actuating means. The snap means such as a springthen snaps the first contact out of engagement with the second contact.The separated parts are carried with the first contact, and thereafteragain resiliently engage the actuating means when freed from theabutment.

In another embodiment of the invention the actuating means comprises arod having a notch on its periphery. The resilient member comprises aspring seated in the notch and carried with the rod from a firstposition to a second position. At the second position, that is, when thefirst contact engages the second contact, the spring is dislodged fromthe notch by being expanded. The first contact which was carried to thesecond position by its engagement with the spring is then free to moverelative to the rod and is snapped back to its first position. Theexpansion of the spring occurs as a result of the rod continuing itsadvancement beyond the position at which the first and second contactsengage. The continued advancement of the rod enables the upper part ofthe notch in which the spring is seated a pass through the centralportion of the spring, thus expanding the spring and dislodging it fromthe notch.

In still another embodiment of the invention, the actuating meanscomprises a rod and the fist electrical contact comprises a circularplate resiliently held to the periphery of the rod by a plurality ofradial springs urging the plate into contact with the rod. In thepreferred form, the springs are placed in radial grooves within theplate, and are attached to rollable members at one end. The rollablemembers are urged into a peripheral notch in the rod by the springs withsufficient pressure to cause the plate to be carried with the rod fromthe first to the second position. At the second position the plateengages and is stopped by the second contact means. Upon engagement ofthe first and second contacts, the rollable members are dislodged fromthe notch and the plate advances axially along the rod opposite to thedirection of the continued advancement of the rod. This axial movementof the plate occurs as a result of a compressed spring acting on theplate. In this manner, the plate is immediately disengaged from thesecond contact and restored to its first operative position.

in an additional embodiment, the pulse-producing snap switch isstructured for mounting on a printed circuit board. For this purpose,the housing of the unit includes a plurality of pronged extensions whichare adapted for snap insertion into receptacles in the printed circuitboard. The board is provided with a recess to receive the advancingactuating means and to removably receive a snap return spring which isoperatively attached to the first contact means.

To the accomplishment of the above, and to such other objects as mayhereinafter appear, the present invention relates to the construction ofa snap-action switch as defined in the appended claims, and as describedin this specification taken together with the accompanying drawings inwhich:

FIG. 1 is a front elevational view in cross section of one embodiment ofa snapaction switch;

FIG. 2 is a similar cross-sectional view of the switch of FIG. 1 shownwith the actuating mechanism in an advanced position;

FIG. 3 is a similar cross-sectional view of the switch shown in FIGS. 1and 2, and illustrates a further operative position of the switch duringthe operating cycle;

FIG. 4 is still another similar view to that shown in FIGS. 1 through 3,and illustrates the return of the actuating mechanism to its originalposition;

FIG. 5 is a cross-sectional view of the switch shown in FIGS. 1-4 takenon lines 5-5 of FIG. 3;

FIG. 6 is a front elevational view in cross section of anotherembodiment of a snap-action switch;

FIG. 7 is a similar cross sectional view of the switch in FIG. 6 withthe actuating mechanism in an advanced position;

FIG. 8 is a similar cross-sectional view of the switch shown in FIGS. 6and 7 and illustrates a further operative position of the switch duringthe operating cycle;

FIG. 9 is still another cross sectional view of the switch shown inFIGS. 6, 7 and 8, and illustrates the return of the actuating mechanismto its original position;

FIG. 10 is a cross sectional view of the switch illustrated in FIGS. 6-9taken on the line l0--10 of FIG. 9;

FIG. 11 is a front elevational view in cross section of still anotherembodiment of a snap-action switch;

FIG. 12 is a fragmentary cross-sectional view of the switch shown inFIG. 11 with the actuating mechanism in an advanced position;

FIG. 13 is a front elevational view in cross section of still anotherembodiment of a snap-action switch;

FIG. 14 is a cross-sectional view of the switch illustrated in FIG. 13with the actuating mechanism in an advance position; and

FIG. 15 is a cross-sectional view taken on lines 15-15 of FIG. 13.

The electrical switch of the invention may be fully understood byreferring to the drawings wherein several embodiments are shown inseveral operative positions. The four switch embodiments shown areseparately illustrated in FIGS. 1 through 5, FIGS. 6 through 10, FIGS.11 and 12, and FIGS. 13 through 16. All of the switches illustratedoperate substantially in the same manner. An actuating means, generallydesignated by the numeral 10, is operatively connected to a base member12. A first electrical contact means designated generally by the numeral14 engages the actuating means 10 through a resilient member 16. Asecond electrical contact means 18 is also operatively connected to thebase 12 and positioned to receive the first contact means 14 to providean electrical connection therewith. A snap means 20 is operativelyconnected to the contact means 14. In the operation of the switch, thefirst contact means 14 is carried with the actuating means 10 and theresilient member 16 to the position of engagement with the secondcontact means 18. Immediately upon the contact of these parts, the snapmeans 20 causes the first contact means 14 to be snapped back to itsoriginal position. The force of the snap means is rendered effective toprovide this result because the resilient member 16 is flexed out ofengagement with the actuating means 10 just as the first and secondcontact means engage, thereby releasing the first contact means fromconnection with the actuating means.

Referring now to the embodiment of FIGS. 1 through 5, the actuatingmeans 10 is there shown as a rod 22 which is attached to a button 24 andis telescopically fittedwithin a housing 26. As illustrated, the rod 22encloses and is slidably mounted about a fixed post 28. A bore 30 isprovided in the central portion of the rod 22 so that the rod mayadvance along the post 28 as shown in FIG. 2. The first electricalcontact means 14 is shown in the form of a circular plate 32 whichsurrounds the rod 22. The plate 32 is provided with conductive strips 34and 36 which are attached to the lower surface 38 thereof. The uppersurface 40 of plate 32 engages the resilient member 16 which comprisesparts 42 and 44 urged into an undercut portion 46 of the rod 22 by aspring 48. The resilient engagement of these parts 42 and 44 with therod 22 causes the parts to be carried with the rod as it advances fromits first or elevated position shown in FIG. I to a second or depressedposition shown in FIG. 2. Consequently plate 32 is also carried with theadvancing rod as shown in FIGS. 2 and 3 until the second contact meansl8is engaged. The second contact means 18 is here shown as electricalterminals 50, 52 54 and 56 (FIG. 5). The terminals 50, 52, 54 and 56 areconnected to the base member 12, project upwardly therefrom into thepath of the plate 32, and act as positive stops for the latter. Thelower portions of these terminals, such as at 58 and 60 (shownfragmentarily) may be electrically connected in any well-known manner toa suitable circuit. As illustrated in FIG. 5 the conductive strips 34and.36 electrically join ter minals 50 and 52 and terminals 54 and 56respectively when engaging these terminals. In this manner electricalcomponents connected to these terminals may be briefly joined togetheror may receive an electrical pulse which is transmitted through theconnections formed by the conductive strips 34 and 36 and the variousterminals. It will be understood that in this and other embodiments thenumber and arrangement of contacts and conductive strips as illustratedare merely by way of example, and may be widely varied.

The snap means 20 illustrated in FIG. I is shown as a spring 62 which isattached at one end to a flanged member 64 and at the other end isreceived in a recess 66 in base 12. The flanged member 64 is attached tothe lower surface of the plate 32 and therefore the spring 62, as it iscompressed by the advancing actuating rod 22, exerts a force on theplate 32. However, the force exerted by the spring 48 on the parts 42and 44 is sufficient to hold those parts within the undercut rod portion46, and hence the contact plate 32 moves with the rod 22 as the latteris depressed until the contact means 14 and 18 engage, as shown in FIG.2. Further advancement of the rod 22 beyond this engaging position, asillustrated in FIG. 3, causes the abutment 68 at the upper portion ofthe undercut section 46 to pass into the central opening 70 formed bythe parts 42 and 44 of member 16 (FIG. 5). Since the abutment 68 is of agreater width than the diameter of the opening 70, the parts 42 and 44are caused to separate. While the force of the spring 48 is stilleffective to urge the parts 42 and 44 against the rod, this force is nolonger sufficient to overcome the force of spring 62 primarily becausethe member 16 is now dislodged from the undercut rod portion. As aresult the plate 32, and more specifically, the conductive strips 34 and36 are snapped up out of engagement with the terminals 50, 52, 54 and 56respectively, as shown in FIG. 4. The spring 62 continues to force theplate 32 and the resilient member 16 upward until the resilient memberis stopped by the flange 72 on the upper portion of the rod 22. At thispoint the resilient member 16 and the plate 32 are restored to theiroriginal position. Continued advancement of the rod 22 performs nofurther function in the operation of the switch. A spring 74 isconcentrically positioned within the spring 62 and operatively connectedbetween the rod 22 and the base 12. This spring is employed to restorethe rod 22 to its original position upon the removal of the actuatingforce from the button 24. When this occurs the undercut rod portion 46returns to registration with the parts 42 and 44, which are then urgedinto portion 46 by spring 48. The switch is then in a condition to againbe actuated.

Because of the force provided by the snap means 20, the actualengagement time of the conductive strips 34 and 36 and the severalterminals 50, 52 54 and 56 is only in the order of a few milliseconds.Thus, the actuating means is forced downward at a rate of speeddepending upon the applied force, but the disengagement of the contactmeans 14 occurs substantially immediately after engagement with thecontact means 18 and is independent of the position of the actuatingmeans 10 after the engagement has been achieved.

Another embodiment of the switch of the invention is shown in FIGS. 6through 10. As there shown the rod 22 of the actuating means isoperatively connected to the plate 76 which is attached to the button24. A spring 78 is affixed at one end to the plate 76 and at the otherend to a shoulder 80 in a housing 26. A concavely formed notch 82 isprovided on the periphery of the rod 22. The resilient member 16 herecom prises a garter spring 84 which normally surrounds rod 22 and isseated in the notch 82. A keeper member 86 is affixed to the uppersurface 40 of plate 32 and partially surrounds the garter spring 84.

A conductive strip 34 is here shown positioned on upper surface 40 ofplate 32. This strip 34 engages third electrical contact means shown asterminals 88 and 90 when this plate 32 is in its upper position as shownin FIGS. 6 and 10. Contact means 18 comprises terminals 92 and 94 (FIG.1.) which are supported in base 12 and project upwardly therefrom. Allof these terminals may be connected at the lower portions 96 and 98 withexternal circuitry.

As illustrated in FIG. 7, when the rod 22 is caused to move downwardlythe garter spring 84 and keeper member 86 are efi'ective to carry theplate 32 into contact with the terminals 92 and 94. The movement of theplate 32 causes the strip 34' to be disengaged from the terminals 88 and90. In the illustration of FIG. 8 the rod 22 has been advanced fartherthan the position shown in FIG. 7 and as a result the spring 84 has beendislodged from the notch 82. At this point, the force provided by thespring 82 is less than the force provided by the snap spring 62 andhence the plate 32 is caused to snap out of engagement with theterminals 92, 94 and to return to its original position, as shown inFIG. 9. The snap action provided by the spring 62 occurs very quicklyafter the engagement of terminal strip 36 and terminals 92 and 94. Thetime of contact is sufficient for a pulse of electrical current to passthrough the terminals to associated electronic equipment, not shown. Asshown in FIG. 9, the conductive strip 34 again contacts the terminals 88and 90 when returned to its original position. Upon a release of theforce from button 24, the rod 22 returns automatically to its originalposition due to the force provided by spring 78 and the spring 84reestablishes itself in the notch 82. Thus, the switch again assumes theoperative condition shown in FIG. 6.

FIG. 11 and [2 illustrate still another embodiment of the switch of theinvention. The component parts of the switch have been similarlynumbered with those parts illustrated in the other drawings andparticularly in FIGS. 6-10. The singular differentiating feature of theswitch in FIGS. 11 and 12 from that shown in FIGS. 6-10 is the convexprojection 100 which is positioned on the periphery of the rod 22. Asillustrated in FIG. 11 the garter spring 84 is positioned below theprojection 100 as the rod 22 moves downwardly. Upon engagement of theconductive strip 36 and terminals 92 and 94, the continued advance ofthe rod 22 causes spring 84 to be expanded by the projection 100, sincefurther movement of the plate 32 is prevented by terminals 92 and 94.The force provided by the compressed spring 62 then snaps the plat 32 toits original position. Release of the actuating force from rod 22 causesthe rod 22 to assume the first operative position as shown in FIG. 11.

FIGS. 13, 14 and 15 illustrate still another embodiment of the switch ofthe invention. The base member 12 is here shown as a printed circuitboard 102 having several conductive areas 104 and 106 exposed at theupper surface 108. The conductive areas 104 and 106 provide electricalcontacts which are adapted to receive the contacts 34 and 36 which arepositioned on the lower surface 38 of the plate 32. The plate 32 isoperatively connected to the carrier section 110. A plurality of springs112, 114 and 116 are radially positioned in grooves formed by the plate32 and section 110 and extend toward the rod 22. A plurality of rollableembers 118, 120 and 122 are positioned at one end of the springs 112,114 and 116 and are seated in the concave notch 124 in rod 22. Each ofthe springs is held against the rollable members by means of a plug suchas at 126, 128 and 130 and the assembly of springs, rollable members andplugs thereby comprise the resilient member designated generally by thenumeral 16.

A large recess 132 is formed in the circuit board 102 to receive the rod22 when it is advanced to the position shown in FIG. 14. A snap spring62 is received at one end in a recessed portion 132 and at the other endengages the lower surface 38 of the plate 32 such as by means of asuitable adhesive or the like.

A plurality of pronged extensions 134, 136 and 138 project from thehousing 26 and are adapted for snap insertion into the receptacles 140,142 and 144 respectively on the printed circuit board 102. With thisstructure, the switch is readily mounted on and removed from the printedcircuit board 102.

When the switch is mounted on the circuit board 102 the spring 62 isreceived in the recess 132 and is slightly compressed against the bottomwall 146. This spring 62 is carried with the switch when it is removedfrom the circuit board 102 due to its engagement with the contact plate32.

The operation of the switch illustrated in FIGS. 13, 14 and 15 issubstantially similar to the operation of the other switch embodimentshereinbefore described. The rollable members 118, and 122 are dislodgedfrom the notch 124 in response to the advance of the rod 22 beyond theposition at which the contacts 34 and 36 on plate 32 form an electricalconnection with the contacts 104 and 106 on circuit board 102. As therod advances beyond this position of initial engagement, the rollablemembers 118, 120, 122 assume the position illustrated in FIG. 14. Thesnap spring 62 then forces the plate 32, carrier section 100, and thesprings, rollable members and plugs to travel in a direction opposite tothe advance of the rod 22. As a result, these members again assume theposition shown in FIG. 13. Spring 78 then acts to restore the rod 22 toits original position.

It will be appreciated that while the description has been limited toseveral embodiments a wide variety of modifications in the switch of theinvention may be made. Terminal engagements shown or suggested in oneembodiment may be used in a different embodiment. The specificstructural means utilized for the various operative parts may be widelyvaried. Additional electrical connections may be utilized with variousterminals which may be connected to any suitable circuitry. Multipoleswitches may readily be provided by a variation in the position of theterminals and size of the conductive strips. It will be apparent thatmany other variations may be made, all without departing from the spiritof the invention.

Iclaim:

1. A snap-action electrical switch comprising a base member, actuatingmeans operatively connected to said base member and movable from a firstposition to a second position, first electrical contact meansoperatively connected in holding engagement with said actuating meansand movable therewith from a first to a second position, secondelectrical contact means at said second position of said first contactmeans and for receiving said first contact means in an electricalconnection upon engagement therewith. means operatively connected tosaid actuating means and effective to release said first contact meansfrom holding engagement with said actuating means when said firstcontact means engages said second contact means, and means to snap saidfirst contact means out of engagement with said second contact meansupon the release thereof from said actuating means.

2. The switch of claim 1, in which said release means comprises aresilient member operatively connected to said first contact means andresiliently engaging said actuating means, and means operativelyconnected to said actuating means and effective to fiex said resilientmember upon the engagement of said first contact means with said secondcontact means, thereby to release said resilient member from saidactuating means for a period sufficient for said snap means to snap saidfirst contact means out of engagement with said second contact means.

3. The switch of claim 2, in which said resilient member comprises amember having two parts and spring means operatively connected to saidparts and effective to urge said parts into engagement with saidactuating means and said flexing means comprises means for separatingsaid parts from said actuating means upon the engagement of said firstand second contact means. I

4. The switch of claim 3, in which said actuating means comprises a rodand said parts form an annular member enclosing said rod, and in whichsaid separating means comprises an abutment on said rod in engagementwith said parts and effective to carry said parts and said first contactmeans with the rod from said first position to said second position,said abutment also being effective to separate said parts upon theengagement of said first and second contacts by passing into the annulusof said annular member upon the continued movement of said rod.

5. in the switch of claim 4, means operatively connected to said rod andeffective to return said rod to said first position after the release ofsaid first contact means.

6. In the switch of claim 2, a projection operatively connected to saidactuating means, said resilient member engaging said projection andbeing carried therewith to said second position.

7. The switch of claim 6, in which said actuating means is a rod andsaid projection is convexly formed on the periphery of said rod, saidresilient member being positioned adjacent said convex projection,thereby to be carried by said projection during the movement of said rodfrom its first position to its second position.

8. The switch of claim 7, in which said resilient member comprises aspring substantially surrounding said rod, said spring being expandedover said convex projection upon the continued movement of said rodbeyond said second position, thereby to be released from carryingengagement with said convex projection.

9. The switch of claim 1, in which said base member comprises a printedcircuit board, and said second electrical contact is operativelyconnected to said board.

10. In the switch of claim 9, a housing operatively connected to saidactuating means and to said circuit board, and a recess in said circuitboard adapted to receive said actuating means as it moves toward andbeyond said second position.

11. The switch of claim 1, in which a third electrical contact is fixedat the first position of said first electrical contact to be thereengaged by said first electrical contact.

12. The switch of claim 2, in which said first electrical contactcomprises a plate having an electrically conductive surface.

13. The switch of claim 12, in which said resilient member engages thesurface opposite to said electrically conductive surface, and is carriedwith said plate when said plate is snapped out of engagement with saidsecond contact means.

14. The switch of claim 1, in which said second contact means isoperatively connected to said base member and projects outwardlytherefrom thereby to provide a stop to prevent further movement of saidfirst contact means beyond its second position of engagement with saidsecond contact means.

15. The switch of claim 2, in which said base member comprises a printedcircuit board, and said second electrical contact is operativelyconnected to said board.

16. In the switch of claim 15, a housing operatively connected to saidactuating means and to said circuit board, and a recess in said circuitboard adapted to receive said actuating means as it moves toward andbeyond said second position.

17. The switch of claim 2, in which a third electrical contact is fixedat the first position of said first electrical contact to be thereengaged by said first electrical contact.

18. The switch of claim 17, in which said first electrical contactcomprises a plate having an electrically conductive surface.

19. The switch of claim 18, in which said resilient member engages thesurface opposite to said electrically conductive surface, and is carriedwith said plate when said plate is snapped out of engagement with saidsecond contact means.

20. The switch of claim 2, in which said second contact means isoperatively connected to said base member and projects outwardlytherefrom thereby to provide a stop to prevent further movement of saidfirst contact means beyond its second position of engagement with saidsecond contact means.

1. A snap-action electrical switch comprising a base member, actuatingmeans operatively connected to said base member and movable from a firstposition to a second position, first electrical contact meansoperatively connected in holding engagement with said actuating meansand movable therewith from a first to a second position, secondelectrical contact means at said second position of said first contactmeans and for receiving said first contact means in an electricalconnection upon engagement therewith, means operatively connected tosaid actuating means and effective to release said first contact meansfrom holding engagement with said actuating means when said firstcontact means engages said second contact means, and means to snap saidfirst contact means out of engagement with said second contact meansupon the release thereof from said actuating means.
 2. The switch ofclaim 1, in which said release means comprises a resilient memberoperatively connected to said first contact means and resilientlyengaging said actuating means, and means operatively connected to saidactuating means and effective to flex said resilient member upon theengagement of said first contact means with said second contact means,thereby to release said resilient member from said actuating means for aperiod sufficient for said snap means to snap said first contact meansout of engagement with said second contact means.
 3. The switch of claim2, in which said resilient member comprises a member having two partsand spring means operatively connected to said parts and effective tourge said parts into engagement with said actuating means and saidflexing means comprises means for separating said parts from saidactuating means upon the engagement of said first and second contactmeans.
 4. The switch of claim 3, in which said actuating means comprisesa rod and said parts form an annular member enclosing said rod, and inwhich said separating means comprises an abutment on said rod inengagement with said parts and effective to carry said parts and saidfirst contact means with the rod from said first position to said secondposition, said abutment also being effective to separate said parts uponthe engagement of said first and second contacts by passing into theannulus of said annular member upon the continued movement of said rod.5. In the switch of claim 4, means operatively connected to said rod andeffective to return said rod to said first position after the release ofsaid first contact means.
 6. In the switch of claim 2, a projectionoperatively connected to saiD actuating means, said resilient memberengaging said projection and being carried therewith to said secondposition.
 7. The switch of claim 6, in which said actuating means is arod and said projection is convexly formed on the periphery of said rod,said resilient member being positioned adjacent said convex projection,thereby to be carried by said projection during the movement of said rodfrom its first position to its second position.
 8. The switch of claim7, in which said resilient member comprises a spring substantiallysurrounding said rod, said spring being expanded over said convexprojection upon the continued movement of said rod beyond said secondposition, thereby to be released from carrying engagement with saidconvex projection.
 9. The switch of claim 1, in which said base membercomprises a printed circuit board, and said second electrical contact isoperatively connected to said board.
 10. In the switch of claim 9, ahousing operatively connected to said actuating means and to saidcircuit board, and a recess in said circuit board adapted to receivesaid actuating means as it moves toward and beyond said second position.11. The switch of claim 1, in which a third electrical contact is fixedat the first position of said first electrical contact to be thereengaged by said first electrical contact.
 12. The switch of claim 2, inwhich said first electrical contact comprises a plate having anelectrically conductive surface.
 13. The switch of claim 12, in whichsaid resilient member engages the surface opposite to said electricallyconductive surface, and is carried with said plate when said plate issnapped out of engagement with said second contact means.
 14. The switchof claim 1, in which said second contact means is operatively connectedto said base member and projects outwardly therefrom thereby to providea stop to prevent further movement of said first contact means beyondits second position of engagement with said second contact means. 15.The switch of claim 2, in which said base member comprises a printedcircuit board, and said second electrical contact is operativelyconnected to said board.
 16. In the switch of claim 15, a housingoperatively connected to said actuating means and to said circuit board,and a recess in said circuit board adapted to receive said actuatingmeans as it moves toward and beyond said second position.
 17. The switchof claim 2, in which a third electrical contact is fixed at the firstposition of said first electrical contact to be there engaged by saidfirst electrical contact.
 18. The switch of claim 17, in which saidfirst electrical contact comprises a plate having an electricallyconductive surface.
 19. The switch of claim 18, in which said resilientmember engages the surface opposite to said electrically conductivesurface, and is carried with said plate when said plate is snapped outof engagement with said second contact means.
 20. The switch of claim 2,in which said second contact means is operatively connected to said basemember and projects outwardly therefrom thereby to provide a stop toprevent further movement of said first contact means beyond its secondposition of engagement with said second contact means.